Physiology and morphology of pulmonary microvascular injury with shock and reinfusion

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Abstract
The effect of hemorrhagic shock and reinfusion of the shed blood on lung microvasculature was studied in 10 anesthetized dogs during a control, a shock (40-50 mm Hg aortic pressure) and a reinfusion period. Pulmonary capillary hydrostatic and oncotic pressures decreased. Lung lymph flow and lymph-to-plasma albumin and globulin ratios increased with shock and with reinfusion, indicating an increased microvascular permeability. Calculated pore radius increased with reinfusion (P < 0.05). Pore number increased both with shock and with reinfusion in 8 dogs. Comparison of the autopsy results of these experiments with those of previous control and shock animals showed that with reinfusion there was a rise in lung wet-to-dry weight ratios and increased granulocytes by light microscopy. By EM the granulocytes were intravascular and there was alveolar wall edema without endothelial or epithelial damage. The morphological changes in the lung with reinfusion apparently are minimal. Granulocytes may cause the observed microvascular injury and interstitial edema.